What is the optimal way to store data-files for testing using travis-ci + Docker?

I am trying to set-up the testing of the repository using travis-ci.org and Docker. However, I couldn't find any manuals about what is the politics on memory usage.

To perform a set of tests (test.sh) I need a set of input files to run on, which are very big (up to 1 Gb, but average 500 Mb).

One idea is to wget directly in test.sh script, but for each test-run it would be not efficient to download the input file again and again. The other idea is to create a separate dockerfile containing the test-files and mount it as a drive, but this would be not nice to push such a big dockerimage in the general register.

Is there a general prescription for such tests?